Magnetic Rayleigh–Taylor Instability in an Experiment Simulating a Solar Loop

A hoop force driven magnetic Rayleigh–Taylor instability (MRTI) is observed in a laboratory experiment that simulates a solar coronal loop. Increase of the axial wavelength λ is observed when the axial magnetic field increases. This scaling is consistent with the theoretical MRTI growth rate ${\gamma }^{2}={gk}-2{\left({\boldsymbol{k}}\cdot {{\boldsymbol{B}}}_{0}\right)}^{2}/{\mu }_{0}\rho $, which implies that if ${\boldsymbol{k}}$ is parallel to ${{\boldsymbol{B}}}_{0}$ (i.e., undular mode), the fastest-growing mode has $\lambda =2\pi /k=8\pi {B}_{0}^{2}/{\mu }_{0}\rho g$.